The arrival of a baby southern brush-tailed rock wallaby over the weekend has excited staff at Tidbinbilla Nature Reserve's breeding program.
The father of the new wallaby was taken from the wild in Victoria and relocated to Tidbinbilla last year.
The male was then placed in a female-dominated group with wallabies deemed to be good mate choices. Six months later he sired his first joey.
''This was the first time a new male has bred with the females. It's very significant,'' the manager of regional operations at National Parks and Catchments, Brett McNamara, said.
There have been 53 rock wallabies born in captivity at Tidbinbilla's Animal Breeding Centre since 2010.
The centre aims to slowly release wallabies back into the wild and Mr McNamara said the newborn had introduced valuable genetics to the vulnerable species.
''It's one of those real 'wow' moments, when you see the joey popping its head out of the pouch, you know hundreds of hours of work and dedication have paid off,'' Mr McNamara said.
''The birth is a great achievement, which the team at Tidbinbilla is justifiably very proud of.''
Geneticists advised the team that a new male had to be introduced to the program, to diversify the genes and ensure survival of the species.
''Low genetic variation makes a population vulnerable to inbreeding, which can be detrimental to long-term reproduction rates,'' Mr McNamara said.
He said the birth spoke volumes for the work done by the staff at Tidbinbilla. ''It really shows their dedication; the wallabies are watched and supervised for 20 hours a day,'' he said. ''These things don't just happen overnight and this birth is a very important step in ensuring long-term survival of the overall population.''
The staff must closely monitor the wallabies to minimise inbreeding, Mr McNamara said.
''There are lot of problems that come from inbreeding: fertility rates can be lower, the animals are more susceptible to diseases,'' he said.
''When you have a captive population you need to be mindful of the inbreeding, cousins or sisters and brothers breeding with each other.'' The ACT played a significant role in the re-establishment of the species.
''As part of the captive breeding program, eight wallabies bred at Tidbinbilla were released into the Grampians national park in Victoria last year,'' Mr McNamara said.
The southern brush-tailed rock wallaby is extinct in the ACT and it is estimated there are fewer than 40 left in the Victorian wild.